A 28-year-old woman with Crohn's disease presents with ileocecal stricturing, recurrent abdominal pain, and weight loss despite adequate mesalamine therapy for 3 months. She has no fever or systemic toxicity. Which is the drug of choice for induction of remission in this patient?

Explanation

## Corticosteroids as First-Line Induction in Moderate–Severe Crohn's Disease **Key Point:** Systemic corticosteroids (prednisolone) are the first-line induction therapy for moderate-to-severe Crohn's disease, particularly when mesalamine has failed and there is no acute surgical emergency. ### Clinical Scenario Analysis This patient has: - **Failed mesalamine therapy** (3 months of adequate dosing) - **Moderate-to-severe disease** (stricturing, weight loss, recurrent pain) - **No acute toxicity** (no fever, no signs of perforation or sepsis) - **Small bowel/ileocecal involvement** (typical Crohn's phenotype) ### Why Corticosteroids Are First-Line Here | Criterion | Mesalamine | Prednisolone | Infliximab | Methotrexate | |-----------|-----------|-------------|-----------|---------------| | **Efficacy in moderate–severe CD** | Poor | Excellent | Excellent | Moderate | | **Onset of action** | Slow (4–6 weeks) | Fast (1–2 weeks) | Fast (2 weeks) | Slow (6–12 weeks) | | **First-line for induction** | No (UC only) | Yes | No (second/third-line) | No (maintenance only) | | **Cost** | Low | Low | Very high | Low | | **Systemic side effects** | Minimal | Significant | Immunosuppression | Hepatotoxicity, teratogenicity | **High-Yield:** In **Crohn's disease**, mesalamine is **NOT effective** for induction — it is used only in mild UC. Corticosteroids are the gold standard for induction in moderate–severe CD. ### Corticosteroid Dosing in Crohn's Disease 1. **Induction:** Prednisolone 0.5–1 mg/kg/day (max 40–60 mg/day) for 1–2 weeks 2. **Taper:** Reduce by 5–10 mg/week over 8–12 weeks 3. **Maintenance:** NOT recommended (ineffective and high toxicity) **Clinical Pearl:** Corticosteroids induce remission but do NOT prevent relapse or maintain remission — they must be tapered and followed by maintenance therapy (azathioprine, 6-mercaptopurine, or biologic agents). ### When to Escalate Beyond Corticosteroids - **Corticosteroid dependence** (relapse on taper or within 4 weeks of stopping) → add azathioprine or biologic - **Corticosteroid resistance** (no response after 4 weeks) → infliximab or other TNF-α inhibitor - **Acute complications** (perforation, toxic megacolon, sepsis) → surgical consultation **Warning:** Do NOT use infliximab as first-line induction in this patient — it is more expensive, requires monitoring, and is reserved for steroid-refractory or steroid-dependent disease. [cite:Harrison 21e Ch 297]